Elasmobranch-repelling magnets and methods of use

ABSTRACT

Devices and methods are disclosed for repelling elasmobranchs with high-pull-force magnets, including devices and methods for reducing by-catch in commercial fisheries and protecting humans from attacks by elasmobranchs.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of U.S. application Ser. No. 14/104,207filed Dec. 12, 2013, which is a Continuation of U.S. application Ser.No. 11/886,109 filed Oct. 7, 2008, now abandoned, which is a U.S.National Phase Application filed under 35 U.S.C. 371 of InternationalApplication No. PCT/US06/08587 filed Mar. 10, 2006, which claims benefitof U.S. Provisional Application No. 60/660,193 filed Mar. 10, 2005 andU.S. Provisional Application No. 60/699,591 filed Jul. 15, 2005, thecontents of each of which are herein incorporated by reference in theirentirety.

INTRODUCTION

This invention relates generally to high-pull-force magnets forrepelling elasmobranchs and methods of using high-pull-force magnets torepel elasmobranchs.

BACKGROUND OF THE INVENTION

Elasmobranchs represent a significant problem in the commercial fishingindustry. Elasmobranchs are often inadvertently caught on fishing hooksand tackle directed at other more commercially valuable kinds of fish.This inadvertent catching of elasmobranchs (or other non-valued fish) iscalled “by-catch.” As many as 100 million elasmobranchs are killed eachyear as by-catch. This loss of life has resulted in a real threat toseveral shark species. Currently, as many as 80 species of shark areconsidered threatened with extinction.

Further, when elasmobranchs are caught as by-catch, fishing operationsreceive no return on their investment since the shark is caught on ahook that might have otherwise brought in a marketable fish.Additionally, the fishing tackle on which a shark is caught often mustbe cut loose for the safety of those working on the fishing vesselcausing a loss of both equipment and time.

Longlining is a commercial fishing method that suffers significantlosses from shark by-catch. Longlining uses multiple baited individualfish hooks with leaders strung at intervals along an often very long(2-3 miles) main fishing line. Longline fishing operations routinelytarget swordfish and tuna. The longline hooks, however, are notselective and elasmobranchs are sometimes caught in greater numbers thanthe intended catch. The result is great loss of life in elasmobranchsand significant financial losses in the longline industry. Elasmobranchscause additional losses in the longline fishing industry by scavengingmarketable fish caught on longlines before the fish may be retrieved forprocessing.

Elasmobranchs also represent a problem in the commercial trawlingindustry. Trawling is a commercial fishing method that catches fish innets. Elasmobranchs cause significant losses for trawlers because theyscavenge fish caught in trawl nets before they are retrieved forprocessing. As such, valuable fish are often lost to shark predation.Also, sharks often tear holes in the nets, resulting in partial orcomplete loss of catch and significant repair costs.

There has been a long-felt need for methods and devices to deterelasmobranchs from commercial fishing lines and nets. Attempts in themiddle of the twentieth century were made to protect trawl nets withelectric discharge devices. (Nelson, “Shark Attack and RepellencyResearch: An Overview,” Shark Repellents from the Sea ed. BernhardZahuranec (1983) at p. 20). Nevertheless, no commercially effectiverepellent has yet to be made available for reducing shark by-catch inthe commercial fishing industry or for reducing loss of valuable fish orfishing tackle to shark predation. Further, Applicant is unaware of anyconsideration in the art of the use of magnets to repel elasmobranchs tolimit by-catch and other losses from elasmobranchs.

U.S. Pat. No. 4,667,431 discloses an electric prod for repelling fish.Within the electric prod, the switch for providing electric current tothe prod is a reed switch, which contains a magnet. However, the magnetis not a part of the repelling portion of the electric prod.

An effective shark repellent would not only be valuable to the fishingindustry but also would be valuable for protecting humans from sharkattacks. No effective repellent has yet to be marketed for limiting therisk of shark attacks faced by humans exposed to elasmobranchs. Over thelast 50 years antishark measures employed to protect humans from sharkhave included electrical repellent devices (Gilbert & Springer 1963,Gilbert & Gilbert 1973), acoustical playbacks (Myrberg et al. 1978,Klimley & Myrberg 1979), visual devices (Doak 1974) and chemicalrepellents (Tuve 1963, Clark 1974, Gruber & Zlotkin 1982). None of theseprocedures proved satisfactory in preventing shark attacks. (Sisneros(2001)). As such, the long felt need for an effective repellent has notbeen satisfied.

Researchers have historically used several bio-assays to determine if arepellent evokes a flight response in shark. One such bio-assay measuresthe effect of a repellent on a shark that is immobilized in “tonicimmobility.” Tonic immobility is a state of paralysis that typicallyoccurs when a shark is subject to inversion of its body along thelongitudinal axis. This state is called “tonic,” and the shark canremain in this state for up to 15 minutes thereby allowing researchersto observe effects of repellents. After behavioral controls areestablished, an object or substance that has a repelling effect willawaken a shark from a tonic state. Researches can quantify the strengthof a repellent effect from these studies.

Another bio-assay employs a Y-shaped maze wherein a shark is exposed toa choice between two paths containing the same olfactory stimulus. Onepath exits the maze without a repellent while the other contains arepellent. If the sharks consistently choose the path without therepellent or consistently become agitated in the path having therepellent, researchers may conclude the repellent is effective.

BRIEF SUMMARY OF THE INVENTION

Applicant has discovered that a high-pull-force magnet is an effectiveelasmobranch repellent useful in limiting by-catch as well as protectinghumans. High-pull-force magnets, known or hereinafter developed, thatare of sufficient strength to repel elasmobranchs are acceptable inaspects of the present invention.

According to a non-limiting embodiment of the present invention, anapparatus for repelling elasmobranchs is provided comprising ahigh-pull-force magnet. Preferably, the high-pull-force magnet is apermanent magnet. More preferably, the high-pull-force magnet is aneodymium-iron-boride magnet. According to a non-limiting embodiment ofthe invention, the high-pull-force magnet may have a nickel coating toprotect the magnet from corrosion. High-pull-force magnets in accordancewith the present invention may have a shape of a cylinder, a cone, acircle, a cube, a disk, a bar, a sphere, a plate, a rod, a ring, a tube,a stick, a block or other shape. In a non-limiting embodiment of theinvention, a high-pull-force magnet may have a hollow portion. In anon-limiting embodiment of the invention, a plurality of high-pull-forcemagnets may be arranged together in a ring. In another non-limitingembodiment of the invention, an apparatus is provided with ahigh-pull-force magnet that is capable of spinning.

High-pull-force magnets of the present invention have a pull forcepreferably of greater than about 50 pounds, more preferably greater thanabout 100 pounds, and most preferably greater than about 200 pounds. Ina non-limiting embodiment, a high-pull-force magnet has a nominalstrength of preferably greater than about 5000 gauss, more preferablygreater than about 10,000 gauss, and most preferably greater than about20,000 gauss. In a non-limiting embodiment, a high-pull-force magnetproduces a magnetic strength preferably of about 5 gauss at a distanceof about 0.01 m to about 1 m, more preferably of about 5 gauss to about14,000 gauss at a distance of about 0.01 to about 0.5 m, and mostpreferably of about 10 gauss to about 320 gauss or greater at a distanceof about 0.1 m to about 0.4 m.

According to a first non-limiting aspect of the present invention, anapparatus is provided comprising a high-pull-force magnet and a buoy, abarge, a net, fishing tackle or any combination thereof. Fishing tacklemay comprise a longline, a main line, a gangion, a lead, a weight, abuoy, a net, or any combination thereof.

According to a second non-limiting aspect of the present invention, anapparatus is provided comprising a high-pull-force magnet and a fishhook. Such fish hook may be individual or attached to longline ormainline and such fish hook may have a single hook or multiple hooks.

According to a third non-limiting aspect of the present invention, amethod is provided for repelling elasmobranchs comprising attaching ahigh-pull-force magnet to a hook, longline, mainline, fishing tackle,gangion, lead, weight, buoy, net, boat or any combination thereof.

According to a fourth non-limiting aspect of the present invention, anapparatus is provided comprising a surfboard and a high-pull-forcemagnet. A high-pull-force magnet may be housed within the surfboard, beattached to the surfboard, or be trailed behind the surfboard in thewater.

In fifth non-limiting aspect of the present invention, a method isprovided for repelling elasmobranchs comprising attaching ahigh-pull-force magnet to a human body or to clothing or accessoriesassociated with a human body. In a preferred technique, ahigh-pull-force magnet may be attached to a human ankle or wrist or maybe attached to a bracelet. A high-pull-force magnet may also be attachedto a belt, a weight belt for diving, or flippers for diving andsnorkeling.

In a sixth non-limiting aspect of the present invention, a kit isprovided comprising a high-pull-force magnet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference tothe accompanying drawings wherein:

FIG. 1 illustrates a traditional circle hook attached to a line and anon-limiting preferred zone (I) for locating a high-pull-force magnet inaccordance with the present invention.

FIGS. 2A-C illustrate non-limiting positions within the zone (I) forlocating a high-pull-force magnet in accordance with the presentinvention. FIG. 2A illustrates a high-pull-force magnet attached to theline above the hook. FIG. 2B illustrates a high-pull-force magnetattached to the hook. FIG. 2C illustrates a high-pull-force magnetattached to the hook shank and clear of the hook eye.

FIGS. 3A-C illustrate non-limiting positions within the zone (I) forlocating a high-pull-force magnet on a J-hook in accordance with thepresent invention. FIG. 3A illustrates a high-pull-force magnet attachedto the line above the hook. FIG. 3B illustrates a high-pull-force magnetattached to the hook. FIG. 3C illustrates a high-pull-force magnetattached to the hook shank and clear of the hook eye.

FIGS. 4A-B illustrate non-limiting positions within the zone (I) forlocating a high-pull-force magnet on a treble hook in accordance withthe present invention. FIG. 4A illustrates a high-pull-force magnetattached to the line above the hook. FIG. 4B illustrates ahigh-pull-force magnet attached to the hook.

FIG. 5 illustrates an exemplary demersal longline with a high-pull-forcemagnet in accordance with the present invention.

FIGS. 6A-B illustrate non-limiting devices for repelling elasmobranchsin accordance with the present invention. FIG. 6A illustrates a buoy andhigh-pull-force magnet and a net with a plurality of high-pull-forcemagnets in accordance with the invention. FIG. 6B illustrates a bargeand a high-pull-force magnet in accordance with the present invention.

FIGS. 7A-C illustrate non-limiting exemplary surfboards with ahigh-pull-force magnet in accordance with the invention. FIG. 7Aillustrates a surfboard with a high-pull-force magnet embedded in orattached to the surfboard in accordance with the invention. FIG. 7Billustrates a surfboard with a high-pull-force magnet that is capable ofspinning in accordance with the invention. FIG. 7C illustrates ahigh-pull-force magnet or magnets that are capable of spinning whenplaced in water. Such a spinning high-pull-force magnet may compriseindividual magnets attached to a hub that is attached to an axle toallow free spinning of the high-pull-force magnet or magnets attached tothe surfboard when water current is present.

FIGS. 8A-C illustrate exemplary accessories for attaching ahigh-pull-force magnet to a human or other subject or object. FIG. 8Aillustrates a belt or weightbelt with a high-pull-force magnet inaccordance with the invention. FIG. 8B illustrates a bracelet orwristband with a high-pull-force magnet in accordance with theinvention. FIG. 8C illustrates flippers for snorkeling or diving with ahigh-pull-force magnet in accordance with the present invention.

FIG. 9 illustrates a plurality of high-pull-force magnets arranged intoexemplary bracelets, belts or attachable rings in accordance with theinvention.

DETAILED DESCRIPTION OF THE INVENTION

“By-catch” is any kind of fish that is caught in a fishing operationwherein the fish is not the object of the fishing operation. Forexample, if the target fish of a longline fishing operation is tuna, anelasmobranch caught on a hook of the longline is by-catch.

“Elasmobranchs” in this specification means one or more elasmobranchiiin the super-orders Galeomorphii and Squalomorphii and ordersSqualiforms (dogfish), Carcharhiniformes (requiem sharks), Lamniformes(mackerel sharks), and certain Orectolobiformes (carpet sharks).Elasmobranchs in this specification includes nurse sharks, anOrectolobiforme, but this specification does not include the othercarpet sharks, such as wobbegongs.

“Gauss” is a measure of magnetic field strength. Gauss is a unit of thedensity of a magnet's flux (or flux density) measured incentimeter-gram-second. A tesla is equal to 10,000 gauss. Gauss andtesla are common units for referring to the power of a magnet to attract(or repel) other magnets or magnetic materials. The Gauss unit describesboth the coercivity of a magnet and its saturation magnetization. Gaussdescribes how strong the magnetic fields are extending from the magnetand how strong of a magnetic field it would take to de-magnetize themagnet.

“Grade” of a neodymium-iron-boride magnet specifies the quality ofmaterial used to construct the magnet. All else being equal, the higherthe quality of materials used to construct the magnet, the greater themagnet's strength. In grading neodymium-iron-boride magnets, a lowergrade, e.g., N35, does not have as much magnetic strength as a highergrade, e.g. N45.

“Longline” refers to a fishing line that may extend up to many mileswherein a mainline extends the full length of the longline andindividual shorter gangion lines attached to the mainline are spaced atset intervals (perhaps several feet or meters or perhaps 1000 feet orgreater apart). Hooks are attached to the individual gangion lines.Hooks may be baited and used to catch target fish. The addition of amagnet of sufficient strength repels elasmobranchs from the baited hooksas well as from the region of the longline generally.

“Nominal strength” of a magnet is measured in gauss or tesla andreflects the theoretical strength of a magnet at its core. Nominalstrength is a function of the grade of a magnet. The higher the grade,the higher the nominal strength. Nominal strength is the strengthnecessary to demagnetize the magnet.

“Pull force” is the attractiveness of a magnet to a mild steel flatsurface in pounds. The formula for calculating pull force is provided indetail herein.

“Target fish” is any kind of fish, the catching of which is the objectof a fishing operation. For example, the target fish of a longlinefishing operation may be tuna. A fish that is caught on the longlinethat is not tuna would not be a target fish.

“Tonic immobility” is the state of paralysis that typically occurs whenan elasmobranch is subject to inversion of its body along thelongitudinal axis of the body, i.e., is belly up. An elasmobranch canremain in this state for up to 15 minutes.

I. HIGH-PULL-FORCE MAGNETS AS REPELLENTS OF ELASMOBRANCHS

It has been discovered that high-pull-force magnets repel elasmobranchs.High-pull-force magnets comprising a pull force of about 50 pounds orgreater introduced into the environment of an elasmobranch havedemonstrated repelling action on elasmobranchs. Likewise, magnetscomprising a nominal strength of greater than about 0.5 teslas (5000gauss) have demonstrated repelling action on elasmobranch. Further,magnets producing about 5,000 mG to about 500,000 mG of magneticstrength at a distance of about 0.01 m to about 1 m from the magnet orabout 10,000 mG to about 320,000 mG of magnetic strength at a distanceof about 0.1 m to about 0.4 m from the magnet have demonstratedrepelling action on elasmobranchs.

High-pull-force magnets may be employed near fishing lines, fish hooksor fishing nets to repel sharks from bait, hooks or nets that have beenset for target fish (not sharks). High-pull-force magnets may also beemployed near people, animals or objects in the water to repelelasmobranchs from frightening or injuring the people, animals orobjects in a particular area.

Sufficient magnetic force to repel elasmobranchs may be measured in anumber of ways. Magnetic force may be measured as pull force, as nominalmagnetic strength at the core of the magnet (in gauss) or at a distanceof interest from the magnet (in gauss). Any measurement known to anartisan practicing the invention may be useful.

The high-pull-force magnet may be a permanent magnet or anelectromagnet. Magnets made of neodymium-iron-boride (NdFeB) arepreferred, given present magnet technology, since these magnets havehigh pull force relative to their physical size. A coating, such asnickel, may protect permanent high-pull-force magnets from corrosion inwater. A preferred NdFeB magnet, in accordance with the presentinvention, may have a grade of about N3 8 through about N50 or greater.

A high-pull-force magnet for repelling elasmobranchs may comprise theshape of a cylinder, a cone, a circle, a cube, a disk, a bar, a sphere,a plate, a rod, a ring, a tube, a stick, a block, a tapered cone, or anyother shape. The high-pull-force magnet may further comprise a hollowportion for stringing, like beads, on a fishing hook, line, belt,bracelet or rings. A high-pull-force magnet comprising a cylinder with adiameter of about 4 inches to about 8 inches and a thickness of about 1inch to about 4 inches is preferred. A magnet with a diameter of about 4inches and a thickness of about 1.5 inches is most preferred.

High-pull-force magnets having a pull force of about 50 pounds orgreater have demonstrated repelling activity on elasmobranch species atdistances as great or greater than 0.3 m from the elasmobranches.Further, a longline fitted with a series of seven magnets set more than100 feet apart has shown repelling activity across an entire longline ofabout 2000 feet. As such, high-pull-force magnets in accordance with theinvention may be used to repel elasmobranches. The repelling activity ofhigh-pull-force magnets may be useful in the commercial fishing industryto reduce elasmobranch by-catch and predation, and useful to repelelasmobranchs from humans in the environment of an elasmobranch or repelelasmobranchs from an area of interest.

The mode of action of high-pull-force magnets on elasmobranchs is notfully understood. While not wishing to be bound by any particulartheory, one plausible theoretical explanation for this surprisingfinding of repellent activity of high-pull-force magnets is thepossibility that electrical eddy currents are generated by anelasmobranch moving through the strong magnetic field created by thehigh-pull-force magnet. The resulting eddy currents may over stimulateampullae of Lorenzini (known to be used by elasmobranchs for navigationand orientation) causing the ampullae of Lorenzini to disorient theelasmobranch or otherwise signal danger to the elasmobranch causingaversive behavior.

Several species of sharks have demonstrated the ability to sensemagnetic fields (Kalmijn, 1978; Ryan, 1980; Klimley, 1993; 2002) butwere not repelled by the use of such magnets. The ampullae of Lorenziniorgan within sharks is used to detect weak electrical fields at shortranges, which functions in the final stages of prey capture: usuallywhen a shark is inches from its prey. A shark's prey emits weak electricfields that are detectable to the shark. As a shark approaches prey, theshark can sense the weak electric field emitted therefrom. In thenatural environment, the detection range of the shark's ampullae ofLorenzini is effective only within inches of an object. As magneticfield strength is increased elasmobranchs sense the magnetic field atmuch greater distances, such as 0.3 m or greater. When a plurality ofmagnets are introduced across a large area or region (such as along afishing longline) sharks may sense a powerful magnetic field at closerange spanning an area/length of 1000 feet.

Magnetic fields generated by high-pull-force magnets such as permanentmagnets are effective repellents for elasmobranchs, excluding certaincarpet sharks in the Orectolobidae family. It is believed thathigh-pull-force magnets are not effective repellents against certaincarpet sharks, particularly spotted wobbegongs (Orectolobus maculatus),because they ambush predators and rely more on visual, olfaction, andlateral line clues than this magnetic sense. This species of shark isfound chiefly in Australia and Indonesia, and does not representsignificant by-catch species or species that are known to be aggressiveagainst humans. Magnets, however, are effective against nurse sharks inthe Orectolobiform family.

While not wishing to be bound by a particular theory, the flux of apermanent magnet, such as an NdFeB magnet, may correlate with thedetection range of the ampullae of Lorenzini. Since, the magnetic fluxfrom a magnet decreases at the inverse cube of the distance from themagnet, at only a few meters distance the magnetic field exerted by themagnet is less than the Earth's magnetic field. As such, repelling ofelasmobranchs with magnets appears to occur within several meters of ahigh-pull-force magnet. Additionally, if a series of high-pull-forcemagnets is spaced in a region, a measurable level of repelling appearsto occur over the entire region.

High-pull-force magnets have been demonstrated by Applicant to act asacceptable repellents of elasmobranchs. The repellent activity ofhigh-pull-force magnets has been shown to be better than existingshark-repellent technology with the exception of certain chemicalrepellents being developed by SHARK DEFENSE LLC that have a greaterrange of action.

A. Magnetic Forces

The force of a magnet may be measured in a variety of ways. Gauss is aunit of the density of a magnet's flux (or flux density) measured incentimeter-gram-second. A tesla is equal to 10,000 gauss. Gauss andtesla are known common units for referring to the power of a magnet toattract (or repel) other magnets or magnetic materials. The Gauss unitdescribes both the coercivity of a magnet and its saturationmagnetization. Basically, it describes how strong the magnetic fieldsare extending from the magnet and how strong of a magnetic field itwould take to de-magnetize the magnet.

The pull force of a magnet is related to the magnet's nominal strengthin gauss or teslas but uses the nominal strength to create a practicalmeasure of a magnets ability to apply a pulling force on materials thatare attracted to a magnetic field, such as ampullae of Lorenzini inelasmobranch. Pull force is related to the flux density of the magnet'smagnetic field (in gauss or tesla) and the shape of the magnet.

Pull force is calculated using the following equation: PullForce=0.576×Br²×(Th)×A¹¹² where Br=Flux Density in KiloGauss,Th=Thickness of Magnetized Surfaces in inches and A=Surface Area of themagnet in inches. Using this equation, a magnet's pull force may bedetermined. A high pull force value for magnets is greater than about 50pounds.

The strength of a magnet's magnetic field is inversely related to thedistance an object is from the magnet. As such, magnets of very lowstrength (or gauss) may repel elasmobranchs if the elasmobranch movesclose enough to sense the magnetic field of the magnet. Ahigh-pull-force magnet having sufficient strength to repel anelasmobranch at sufficient distance such that the elasmobranch isdeterred from striking a baited hook or coming near a person or othersubject is preferred. It is more preferred that a high-pull-force magnethave a pull force of at least 100 pounds to provide sufficient magneticforce to repel an elasmobranch away from a baited hook or a personbefore the elasmobranch may bight the hook or harm the person. Becausean elasmobranch may act to strike a hook or person at a distance fromthe target, the stronger the high-pull-force magnet, the more effectiveit will be. It has been reported that magnets have a beneficial healtheffect in humans and a negative health effect in humans at high power.Applicant makes no representation herein of the safety of use ofhigh-pull-force magnets by humans during short- or long-term use.

II. METHODS AND DEVICES FOR MAGNETIC REPELLENTS

A. Magnets

Exemplary and non-limiting high-pull-force magnets in accordance withthe invention may be constructed of any material that is capable ofgenerating a magnetic field without requiring an outside energy source(such a permanent ferrous magnet). Magnetism may be generated in anymanner known to the skilled artisan who is practicing aspects of theinvention.

There are many varieties of permanent magnet materials includingneodymium magnets (which are some of the most powerful permanent magnetsknown at this time), samarium-cobalt magnets, ceramic magnets, plasticmagnets, Alnico magnets as well as traditional ferrous magnets. Anymagnetic material having sufficient pull force may be used as arepellent of elasmobranchs.

Exemplary permanent magnets include neodymium-iron-boride (NdFeB)magnets, ferrous metal magnets, samarium-cobalt magnets, or any othermagnetic material. High-pull-force magnets may be flexible orinflexible. High-pull-force magnets may be made of sintered metal powderor of metal or any other magnetizable material.

A preferred magnetic material for high-pull-force magnets contemplatedwithin an aspect of the invention is NdFeB. NdFeB is a more preferredmaterial than ferrous magnets, flexible magnets or samarium-cobaltmagnets. Flexible magnetic strips may be constructed from magneticpowder such as ferrous or other powder mixed with polymer bondingmaterial such as rubber-like material. Samarium-cobalt magnets are lesspreferred in that they may be more brittle than other magnets.

In selecting a high-pull-force magnet, a pull force of about 50 poundsor greater is preferred. A pull force of about 100 pounds or greater ismore preferred since the impact of the magnetic field will felt at agreater distance from the magnet.

Neodymium-iron-boride magnets, commonly called “rare earth,” “NdFeB,” or“NIB” magnets, typically meet or exceed residual inductances greaterthan about 5,000 gauss, which is preferred. Residual inductance defineshow changing magnetic fields generate electric currents and is alsomeasured in gauss.

In order to maximize high pull force, the surface area of a magnet maybe maximized. For example, a 6″ diameter by 2″ thick cylindrical N38NdFeB magnet (nominal strength 13000 gauss; pull force 1042 pounds) maybe effective in repelling elasmobranchs at a range of 6″.

A plurality of magnets may be employed to repel elasmobranchs. Forexample, 1″ cube magnets may be arranged in a 12″ long bar and used torepel elasmobranchs. The cube magnets may be of any magnetic materialcapable of producing sufficient magnetic strength at any distance ofinterest from the magnet to repel elasmobranchs.

Alternatively, a plurality of 1″ cube magnets may be arranged linearlywith a distance between each magnet. The magnets may be arrangedlinearly with positive poles facing one another or may be arranged withpositive poles facing negative poles. Smaller magnets are also effectivein repelling elasmobranchs and may preferably be arranged to maximizesurface area presented to an oncoming elasmobranch.

Metals with special magnetic properties may be used in conjunction withpermanent magnets in order to maximize or shape the magnetic fluxprofile of the magnet and thereby increase the pull force by directingthe magnetic force more powerfully at an elasmobranch of choice. Forexample, holmium metal, which possesses the highest magnetic moment ofthe known elements, may be used to optimize the magnetic flux profile. A1.5″ holmium ring with a drilled 0.5″ diameter center, coupled to anNdFeB 1.5″ diameter cylindrical magnet, produced aversive reactions inimmobilized sharks when the holmium end was oriented to the shark'snares. Other materials that may also be used, among others, forcontrolling the shape of the magnetic flux of a magnet may begadolinium; pyrolytic graphite; mu-metal (a nickel-iron alloy comprisingcopper and molybdenum that has a very high magnetic permeability and is,therefore, very effective at screening magnetic fields); and bismuth.

To protect permanent magnets from corrosion when placed in water,permanent magnets may be coated with any coating that will reducecorrosion and preserve the magnetic force of the magnet. For example,magnets may be coated with nickel, rubber, plastic, acrylic, enamel,paint or other coating. Nickel-plated NdFeB magnets are an example ofpreferred high-pull-force magnets so long as the coating remains intact.

It may be desirable to encase a magnet in paint. Black paint is apreferred paint color to avoid underwater reflections and flashes ofsunlight from the magnet's surface that can act as an attractant. Amagnet may also be enclosed in any waterproof housing, such as a polymercoating.

B. High-Pull-Force Magnets in Combination with Hooks

A non-limiting aspect of the present invention is the use ofhigh-pull-force magnets to repel elasmobranchs from baited hooks.Exemplary and non-limiting combinations of a high-pull-force magnet anda hook are illustrated in FIGS. 1-4. For example, in FIG. 1, anexemplary and non-limiting circle hook and line (100) are illustratedwherein a circle hook (140) is attached to a line (150) along with anexemplary and non-limiting Zone I in the circle hook and line where ahigh-pull-force magnet may be placed or affixed. The preferred region(Zone I) for magnet placement along the line (150) or shank (142) of thehook is any region wherein the affixed or placed magnet does notobstruct the hook gap distance (Zone II). Not more than 20% of the hookgap distance (Zone II) is preferably obstructed by the magnet such thatthe hook is not prevented from being baited or setting in the corner ofthe mouth of a target fish. Nevertheless, any arrangement wherein thehook is not prevented from catching target fish is acceptable. Taperedconical designs (not illustrated) are contemplated such that thediameter of the high-pull-force magnet at the hook end is smaller thanthe diameter of the high-pull-force magnet at the line end of Zone I.

Exemplary and non-limiting combinations of a high-pull force magnet on ahook and line are illustrated in FIGS. 2A-C. As in FIG. 2A, ahigh-pull-force magnet (210) may be placed in proximity to a circle oroffset circle hook (240) attached to a line (250) so that it rests onthe hook eye (241) providing an exemplary embodiment such as thehook-magnet combination embodied at 260. As in FIG. 2B, ahigh-pull-force magnet (210) may be placed in proximity to a circle oroff-set circle hook (240) so that it rests on the shank (242) of thehook providing an exemplary embodiment such as the hook-magnetcombination embodied at 270. As in FIG. 2C, a high-pull-force magnet(210) may be placed on a circle or offset circle hook (240) so that itis secured to the outside of the shank (242) and the hook eye (241)providing an exemplary embodiment such as the hook-magnet combinationembodied at 280. A high-pull-force magnet may be affixed outside theshank (241) of a hook simply by the magnetic force of thehigh-pull-force magnet. Vinyl electric tape (not illustrated) may beused to secure the high-pull-force magnet. Black vinyl tape is preferredto reduce reflections of light.

High-pull-force magnets may be provided in any shape. It is preferredthat a magnet's shape not significantly obstruct the hook gap distance(zone II). The magnet may comprise a hole through which a lead, organgion, or mainline or other filamentous object may pass. Exemplarynon-limiting shapes may include a cube or block of any size or otherobject having at least one plane comprising four right angles and a holepassing through the object such that fishing line or other filament maybe passed through to affix the magnet in place on fishing tackle orother object. Alternative, non-limiting shapes may also includecylindrical or other circular, oval or oblong three-dimensional shapeshaving a hole passing through some portion of the shape. Alternative,non-limiting shapes may also include a hollow pyramid or a hollowtrapezoid.

Alternative, non-limiting shapes may also include a solid cube orsimilar shape, a solid rectangle or similar shape, a solid bar orsimilar shape, a solid pyramid or similar shape, a solid trapezoid orsimilar shape or any other shape. Magnets may be shaped as a ring, atrapezoid, a series of trapezoids, a series of trapezoids arranged in alarger ring pattern, a cone, a tapered cone, a narrow or wide cylinderor in the shape of a Billy club. Preferably, the shape when combinedwith a hook provides a hook in proximity to a magnet comprisingsufficient magnetic field strength to repel elasmobranchs.

Exemplary and non-limiting combinations of a high-pull-force magnet anda hook are also illustrated in FIGS. 3A-C. As in FIG. 3A, ahigh-pull-force magnet (310) may be placed in proximity to a j-hook(340) on a line (350) such that it rests on the hook eye (341) providingan exemplary embodiment such as the hook-magnet combination embodied at360. As in FIG. 3B, a high-pull-force magnet (310) maybe placed inproximity to a j-hook (340) such that it rests on the shank (342) of thehook providing an exemplary embodiment such as the hook-magnetcombination embodied at 370. As in FIG. 3C, a high-pull-force magnet(310) may be placed on a j-hook (340) such that it is secured to theoutside of the shank (342) and the hook eye (341) providing an exemplaryembodiment such as the hook-magnet combination embodied at 380. Asdescribed above in the illustration of FIG. 2, magnets may be providedin any shape.

Exemplary and non-limiting combinations of magnet and hook are alsoillustrated in FIGS. 4A-B. In FIG. 4A, a high-pull-force magnet (410)may be placed in proximity to a treble hook (440) on a line (450) suchthat it rests on the hook eye (441) providing an exemplary embodimentsuch as the hook-magnet combination embodied at 460. As in FIG. 4B, amagnet (410) may be placed in proximity to a treble hook (440) such thatit contacts the shank (442) of the hook providing an exemplaryembodiment such as the hook-magnet combination embodied at 470.

A hook in accordance with the invention may be any hook that is capableof catching target fish. The hook may comprise stainless steel, steel,galvanized metals, ferromagnetic metals or any other material, metallicor plastic or any other composite.

A high-pull-force magnet in accordance with an aspect of the inventionmay comprise any magnetic material.

C. High-Pull-Force Magnets on Longlines

An exemplary and non-limiting method of repelling elasmobranchsinvolving repelling elasmobranchs from longlines in accordance with theinvention is illustrated in FIG. 5. A longline (500) may be deployedfrom a boat (561) to fish for a target fish of interest. The main line(550) of the longline may be attached to a buoy (520) and at a setdistance from the buoy may be attached to an anchor (562). A set ofgangions (530) with hooks (540) may be attached to the mainlinebeginning at the anchor (562) and may be spaced sufficiently to limitinteraction between individual gangion lines (530). Each hook may have amagnet (510) mounted resting on the hook eye (541). Alternatively, themagnet may be mounted on a hook shank (542) or may be secured to theoutside of the hook (540). The hooks may be baited. The longline may bea demersal longline such that the main line is proximal to the ocean orotherwise water's floor. The longline may be a pelagic long line, suchthat the main line is nearer to the surface of the water, suspending inthe water column, typically at about 100 to about 500 feet below thesurface. In the aspect of the invention where the longline is a pelagiclongline, anchors (562) may have less weight or may be absent from thelongline apparatus. The longline may also be a semipelagic longlinewherein the mainline is further down the water column from the surfaceas compared to a pelagic line but is not proximal to the water's flooror is not proximal to the water's floor on at least one end of thelongline. Use of magnets with longlines reduces by-catch ofelasmobranchs.

Longlines comprising magnets may be handled in the commercialenvironment in a manner similar to those practices known in the art oflongline commercial fishing. Because hooks must be carefully managed tocontrol tangling and hooking of objects on a longlining boat, includingother portions of the tackle of the longline, commercial fishingoperations and those of skill in the art will recognize how to handlelonglines with hooks. High-pull-force magnets on longlines likewise maybe handled in the same manners as one would consider appropriate in theart to avoid entanglements of magnets or magnets sticking together. Thelong distances between gangions (often more than 100 feet) allow forcommercial fishing operators to provide sufficient distance betweenmagnets to avoid the magnets sticking together during fishing or duringhandling of tackle. Further, high-pull-force magnets used for longlinesare of sufficiently small size and magnetic force that the magnets maybe separated from one another by hand if they do become stuck together.

As described above, high-pull-force magnets of any size may be used incombination with a longline hook so long as the target fish may becaught on the hook. An exemplary high-pull-force magnet on a longlinehook may be 2″×0.25″×2″. Smaller high-pull-force magnets are alsoacceptable. High-pull-force magnets of less than 0.5″ cubed may beappropriate for smaller hook settings. Smaller high-pull-force magnetshaving sufficiently powerful magnetic fields such as N48 grade NdFeB aremore preferred.

D. High-Pull-Force Magnet Repellents on Buoys, Nets and Barges

An exemplary and non-limiting method of repelling elasmobranchs with ahigh-pull-force magnet or a plurality of high-pull-force magnets placedon a buoy or barge or net is illustrated in FIGS. 6A-B. Buoys withhigh-pull-force magnets as their weighted bases are shown as element 660and 661 in FIG. 6A. The floating portion of the buoy (620) allows thebuoy to float while the high-pull-force magnet portion of the buoy (610)remains in the water because of its weight. A series of buoys comprisinghigh-pull-force magnets may be placed in a region to repel elasmobranchsor may be placed around a swimming area or rescue area to repelelasmobranchs. A series of buoys with high-pull-force magnets may beaccompanied by a series of high-pull-force magnets submerged (611) in anarea of interest, such as a swimming area. As illustrated in FIG. 6B,very large high-pull-force magnets may be placed on a large floatingbarge (670) comprising a high-pull-force magnet (610).

An exemplary and non-limiting device for repelling elasmobranchs with aplurality of magnets is illustrated in FIG. 6A as element 600, anelasmobranch repelling net apparatus. Buoys (660 and 661) may beemployed to float a net (650) comprising a series of magnets (640) heldwithin the net and magnetic rings (630) holding the ropes of the nettogether. The net may be strung to the bottom of the water column usingweighted magnets (611). The net may be anchored to a specific locationto provide a physical barrier. The net may provide a curtain of magneticfield to repel elasmobranchs from an area or to keep elasmobranchs fromentering an area of interest, such as a swimming or working area. A net(650) comprising magnets such as those illustrated as elements 610, 611,630 and 640 may also be used to trawl for fish, shrimp or other aquaticspecies. In another non-limiting aspect of the invention,high-pull-force magnets may be placed in aquaculture cages to repelsharks from predation or scavenging of cultured stock. High-pull-forcemagnets are useful to prevent damage by elasmobranchs to aquaculturecages, nets or other equipment.

E. Surfboard Fitted with High-Pull-Force Magnet

A non-limiting repelling device in accordance with the invention maycomprise a surfboard comprising a high-pull-force magnetic device. FIG.7A illustrates exemplary surfboards in accordance with an aspect of theinvention. A surfboard (720) may comprise a high-pull-force magneticdevice such as a permanent high-pull-force magnet (710) imbedded,affixed, attached or otherwise associated in any manner contemplated byone of skill in the art with the surfboard. A permanent high-pull-forcemagnet may be pressed into a space drilled into the surfboard (730). Itmay also be affixed with glue, waterproof tape, Velcro or any othermechanism known in the art now and hereafter.

In an alternative non-limiting example in FIG. 7B, a surfboard (750) maycomprise a high-pull-force magnet or plurality of high-pull-forcemagnets in association with one another wherein the high-pull-forcemagnet or magnets are capable of spinning when placed in water (740).Such a spinning high-pull-force magnet (740) may comprise individualmagnets attached to a hub (770) that is attached to an axle (760) toallow free spinning of the high-pull-force magnet or magnets attached tothe surfboard (750) when water current is present.

A high-pull-force magnet may be enclosed in the body of a surfboard orother watercraft or may be trailed behind a surfboard, other watercraftor swimmer.

F. High-Pull-Force Magnet Repellents on Swimming and Diving Clothing andAccessories

One exemplary non-limiting aspect of the present invention comprises amagnetic material for producing a magnetic field near a swimmer or diveror other person or object in an elasmobranch environment.

High-pull-force magnets, such as, for example, high-pull-force NdFeBmagnets or other high-pull-force permanent magnets may be worn as abracelet or a band or otherwise placed in proximity of a person orobject. An increase in the number of high-pull-force magnets and anincrease in the grade of high-pull-force magnets that may be wornincreases the magnetic field around the wearer and increases therepelling activity of the bracelet, band or other magnet article.Research on captive nurse sharks suggests that such a bracelet iseffective in repelling sharks. Using a vinyl-walled tank,high-pull-force magnets were waved outside the tank wall near a restingnurse shark inside the tank. The shark had no olfactory, motion, sound,or visual clues. In seven separate observations, the nurse shark alwaysrapidly fled from its resting site once the high-pull-force magnet waswaved on the tank wall near the subject.

In a non-limiting example, an omnidirectional permanent magnetic fieldmay be affixed or arranged near a subject or object exposed to anelasmobranch environment. The permanent magnetic field may be generatedfrom, for example, a permanent magnet or an electromagnet. A permanentmagnet may be affixed, for example, to any portion of a swimmer's ordiver's body such as the head, the leg, the arm, the torso, the ankle,the wrist, or any other portions of the body.

FIGS. 8A-C illustrate non-limiting examples of permanent high-pull-forcemagnets (810) attached to a belt (801) (FIG. 8A) or bracelet (802) (FIG.8B) or flippers (803) (FIG. 8C).

FIG. 9 illustrates a variety of non-limiting alternative designs forbracelets, belts or rings constructed solely from high-pull-forcemagnets. A plurality of bar magnets (981) (982) (983), larger sphericalmagnets of varying sizes (984) or smaller spherical magnets (985) may beshaped into a bracelet or belt. A plurality of discs (986) may be shapedinto a bracelet or a belt or any shape that keeps the magnets inproximity to the body. Two concave bar magnets (987) may be placed onthe ankle or wrist opposite each other such that they are held in placeon the ankle or wrist by attractive magnetic forces.

The bracelets in FIG. 9 may be flexible and may be modulated to fit aportion of the body. Individual magnets of the bracelet may be easilyseparated and placed on the ankle or wrist.

The disks (986) may be magnetized on their edges and not magnetized ontheir faces. As such, the disks may be assembled as a ring usingmagnetic connections on their edges. The disks may be manipulated andmay be returned to a circle. As such, they may conform to a ring toattach to any type of clothing, equipment or body part to which a ringmay be attached.

High-pull-force magnets may likewise be attached to clothing or wateraccessories such as swim trunks, wet suits, headbands, flippers, gogglesor other piece of clothing or accessory. High-pull-force magnets may besewn into such clothing or may be affixed with tape, glue, Velcro or anyother mechanism for affixing to clothing or accessories for swimming,diving or otherwise working or playing in water.

Many human-shark interactions in shallow water, especially around theState of Florida in the United States, are hypothesized to be “mistakenidentity” by the shark in water with poor visibility. The blacktip shark(C. limbatus) and nurse shark (G. cirratum) are often implicated inthese encounters. The sharks do not have an olfactory clue in most ofthese “mistaken identity” cases. A series of high-pull-force magnets,such as NdFeB high-pull-force magnets or other strong permanenthigh-pull-force magnets, may be used as means to repel the shark as itapproaches within a few inches of the magnets. With a stronghigh-pull-force magnet, such as NdFeB, or an increased number ofhigh-pull-force magnets, to increase magnetic field strength, repellentactivity increases and the chance that a shark will be repelled prior toan investigatory bump or bite is greatly increased.

The invention is further described with the following non-limitingexamples, which are provided to further illuminate aspects of theinvention.

III. EXAMPLES Example 1 Pull Force of High-Pull-Force Magnets

Some of the high-pull-force magnets that have been used in examples inthis application are listed below in Table 1 with calculation of thepull force of the respective high-pull-force magnets based on thegeometry, size, grade and nominal strength (conservative BR) of thehigh-pull-force magnet.

TABLE 1 Conservative Pull Force Geometry Size Grade Br (Gauss) (pounds)Puck 4″ × 1.5″ N38 13000 521 magnet Bar 6″ × 2″ × 0.5″ N48 13800 191.31Hollow 1″ × 1″ with 3/16″ N42 13200 72.75 cylinder hollow center 2stacked 0.472″ × 1.97″ × N50 14100 46.7 hollow 0.24″ hollow cylinderscenter Cube 1″ × 1″ × 1″ N48 13800 110.5 longlines

Pull force is descriptive of the attractiveness of a magnet to a steelflat surface. A shark is not a magnetic steel surface, but it does havea surface (likely the ampullae of Lorenzini) that interacts with themagnetic field of the magnet. As such, pull force is an appropriatemethod for measuring interaction of an elasmobranch with a magneticfield.

Example 2 High-Pull-Force Magnets as Repellents on Longlines

The following example demonstrates the elasmobranch repellent activityof high-pull-force magnets of greater than about 150 pounds of pullforce on long lines. High-pull-force magnet treatments were evaluated onone demersal longline located in the middle of a large lagoon. Adjacentlonglines in the same lagoon produced large shark catch (generallygreater than two sharks over the 15 hooks on a line).

Seven hooks on a demersal longline of about 1000 feet were treated with2″×0.25″×2″ NdFeB N48 magnets (nominal force 14,000 gauss; pull forceabout 161 pounds). The high-pull-force magnets were secured ateven-numbered hooks on the longline, directly above the eye of the hookand strapped to the gangion leader with black vinyl electrical tape. Allhooks received bait. If the bait was lost during the experiment, thehook was re-baited while the high-pull-force magnets were not removed orreplaced; only the bait was exchanged.

A large nurse shark of about 250 cm was captured on a control hook (hookwith no magnet affixed) after a second re-bait. From earlier longlinetrials at this spot, a much higher nurse catch was expected on thisline, especially since the high-pull-force magnets acted as weights andheld the baits closer to the sea floor. However, only one nurse sharkwas caught. As such, it is believed sharks were repelled from the entirelongline by the series of high-pull-force magnets affixed thereto.

TABLE 2 1^(st) Set 2nd Re- Hook Treatment Bait Bait bait Bait SpeciesCaught  1 None Barracuda Barracuda Tuna  2 Magnet Barracuda BarracudaBarracuda  3 None Barracuda Barracuda Barracuda  4 Magnet BarracudaBarracuda Tuna  5 None Barracuda Barracuda Tuna  6 Magnet BarracudaBarracuda Tuna  7 None Barracuda Barracuda Tuna  8 Magnet BarracudaBarracuda Tuna  9 None Barracuda Barracuda Tuna 10 Magnet BarracudaBarracuda Tuna 11 None Barracuda Barracuda Tuna 12 Magnet BarracudaBarracuda Tuna 13 None Barracuda Barracuda Tuna Nurse, 250 cm 14 MagnetBarracuda Barracuda Barracuda 15 None Barracuda Barracuda Tuna

Example 3 High-Pull-Force Magnets as Repellents on Longlines

The following example demonstrates the elasmobranch repellent activityof high-pull-force magnets of greater than 50 pounds of pull force onlong lines. A first demersal longline with eight hook sets was baitedwith barracuda flesh and placed in open water. No high-pull-forcemagnets were placed on the hooks. Five sharks were captured on thelongline over 24 hours representing 5 separate shark species ranging insize from 97 cm to 240 cm. See Table 3.

TABLE 3 Hook Species  1 1. Tiger (F), 235 cm   2. Nurse (F) 231 cm   3.Sharpnose (F), 97 cm  2  3  4 Nurse 240 cm  5  6  7  8  9 10 11 12 13 14Blacknose 115 cm 15

A second demersal longline with fifteen hook sets was baited with squidand placed in the same position in open water as the first demersallongline discussed above for 67 hours. The trial with the seconddemersal longline was run three months after the trial with the firstdemersal longline. Seven of the fifteen hooks were treated with 1″×1″×1″neodymium-iron-boride grade N48 cube magnets (pull force of about 110pounds; nominal force around 14,000 gauss) with the high-pull-forcemagnet secured to the outside of the hook shank using the magnetic forceof the hook and black vinyl electric tape. All hooks received bait.During re-baits, the high-pull-force magnets were not removed orreplaced; only the bait was exchanged.

Two small sharks were caught on the second demersal longline. Ablacknose shark of 110 cm was caught on a control line with no magnets.A sharpnose shark of 80 cm was caught on high-pull-force magnet line.The large decrease in shark catch between the first demersal longlinetrial (five relatively large sharks for their species) and the seconddemersal longline trial (two relatively small sharks) was ascribed tothe presence of magnets along the longline. See Table 4.

TABLE 4 Hook # Trtmt Bait Species Caught  1 control squid  2 magnetsquid  3 control squid  4 magnet squid  5 control squid  6 magnet squidsharpnose 80 cm  7 control squid blacknose 110 cm  8 magnet squid  9control squid 10 magnet squid 11 control squid 12 magnet squid 13control squid 14 magnet squid 15 control squid

A third demersal longline was set with 15 hooks in the same position asthe first and second demersal longlines discussed above. The thirddemersal longline was set within a day of the second demersal longline.Seven of the eight hooks were fixed with magnets at the same position.Magnets were small NdFeB grade N50 hollow cylinders (12 mm outerdiameter×6.1 mm inner diameter). Two magnets were placed on each hookcreating a total magnet length of 50 mm. Together the magnets have apull force of about 47 pounds and a nominal force of 14,100 gauss. Thedemersal line was placed in the same open water position as bothdemersal lines in Example 3. Within a 24-hour period, 3 large (>200 cm)tiger sharks were captured, 2 on magnet treatments. The smaller (lesspowerful) magnets did not repel tiger sharks.

Since a larger number of sharks (and of larger size) were caught on thefirst and third longlines, the three trials presented in this exampledemonstrate that sharks were repelled from the second longlinecomprising magnets of sufficient magnetic strength to repel sharks.Together, the three longline trials contained in this exampledemonstrate repelling of sharks by magnets of sufficient magneticstrength to repel sharks across a longline.

Example 4 High-Pull-Force Magnet Terminates Tonic Immobility at Greaterthan 30 cm Distance

Preliminary research conducted on the effects of specific magneticfields on shark behavior suggests that weak magnetic fields (0.3-0.5Gauss) produced by electromagnets had no significant repelling effect onjuvenile nurse sharks, Ginglymostomata cirratum, and juvenile lemonsharks (Negaprion brevirostris) under tonic immobility, however, verystrong magnetic fields (i.e. about 14,000 Gauss or 1.4 Tesla) producedby large (4″diameter×1.5″ height) “rare earth” magnets(neodymium-iron-boride; NdFeB) (13000 gauss, pull force of 521 pounds)had a significant repelling effect on both shark species at distances of0.3 m or less. Additional experiments on captive sharks in an offshore,sandy bottom, fenced-in enclosure were done with NdFeB high-pull-forcemagnets buried under the sand. Exposure of the sharks to the buriedmagnets resulted in “violent reorientation” as the captive sharks cameinto proximity of the buried high-pull-force magnets.

Example 5 Y-Maze Preference Bioassays

A Y-maze was constructed to establish a preference test to determine therepellent activity of magnets on elasmobranchs. The maze was constructedof three sections of clear acrylie 8 inch diameter tubing, connected at33° angles to form a Y-shape. Slotted guides were secured to theentrances of each tube, to allow the insertion of a moveable door, whichobstructs one exit. The entire maze was submerged in a test tank. Sharkswere allowed to freely enter the maze and exit the maze. Ahigh-pull-force magnet was placed, south pole facing the maze junction,in an obstructed leg of the maze, preventing an exit from the maze inthat direction if that obstructed leg is chosen. The diameter of thetubing was sufficient to allow juvenile nurse sharks, juvenile lemonsharks, and juvenile wobbegong sharks to enter and pass through, but itwas small enough to prevent the specimen from turning around within thetube.

For each trial, uncooked shrimp were used as a reward, and the southpole of a 4″ diameter NdFeB nickel-coated cylindrical high-pull-forcemagnet (pull force 521 pounds; nominal force about 13000 gauss) wasplaced in the obstructed leg. One shrimp was positioned midway into theentrance tube to entice the shark to enter the maze. Two shrimp wereplaced midway into the exit tube, and two shrimp were placed midway intothe tube containing the magnet. When the shark entered the maze andreached the Y-junction, the shark was presented with approximately theequal odor gradient from the shrimp in the exit tube and the tubecontaining the magnet. If the shark chose the maze without thehigh-pull-force magnet, it was rewarded with two additional shrimp as itexited. If the shark chose the maze with the high-pull-force magnet, itwas subjected to an exponentially-increasing magnetic field as it moveddown the tube. The shark could only physically back out of thehigh-pull-force magnet tube and into the junction. Sharks that movedinto the magnet and attempted to back out were visible traumatized.Feeding observations regarding the two shrimp in the high-pull-forcemagnet tube were made.

Each trial was scored as follows:

-   -   +1 Subject enters the maze    -   +1 Subject exits the maze    -   +1 Subject takes the first reward shrimp just after entry        (teaser)    -   +2 The unobstructed path is chosen at the junction    -   +3 At least one reward shrimp in the unobstructed path is taken    -   −2 The obstructed path is chosen (magnet) at the junction    -   −3 The specimen enters more than 6″ into the obstructed path and        is visibly struggling.

A perfect score=7 for each trial. If a shark became traumatized andrequires removal from the maze for its own safety, a score is calculatedup to the point of the rescue. A rescue is made whenever a subjectappears to be highly distressed, and a physical injury is likely.

For example, a nurse shark entered the maze, took its first rewardshrimp, and immediately chose the unobstructed path. As it exited, ittook its two reward shrimp, and exited the maze without a change inbehavior.

Score=1+1+2+3=7

In another example, a nurse shark entered the maze and took its firstreward shrimp. It chose the obstructed path but was repelled by themagnet. The shark backed up into the Y-junction; reoriented itself; andexited the unobstructed path without taking the two shrimp available inthe unobstructed path.

Score=1+1−2+1=1

In yet another example, a lemon shark entered the maze and took itsfirst reward shrimp. It chose the obstructed path, and then continueddown the magnet to within 6″ of the magnet. It became extremelydistressed and a rescue was made.

Score=1+1−2−3=−3

In an investigation, three nurse sharks were subjected to the maze.Shark 1 was subjected to the maze five times. Shark 2 was subjected tothe maze 5 times but only entered the maze 4 times. Shark 3 wassubjected to the maze once but required rescue when it encountered themagnet and subsequently died, apparently from stress related to exposureto the magnet. The magnet in the obstructed maze was a 4″×1.5″cylindrical NdFeB magnet of grade N48 (13000 gauss, 521 pounds pullforce). The results are contained in Table 5.

TABLE 5 Obstruction Nurse 1 Nurse 2 Exit (Lg.) (Med.) Nurse 3 Trial 1 L1 1 −4 Trial 2* L 5 1 (rescue Trial 3 R 4 3 performed) Trial 4 L 4 4Shark would Trial 5 R 5 Did not enter not re-enter maze in subsequenttrials

The data suggest that Nurse 1 has learned to navigate the maze, retrievea reward, and exit without distress. Nurse 2 appears to be learning, butdid not re-enter on the fifth trial. Nurse 3 had to be rescued. It wasnotably distressed by the magnet. Unfortunately, Nurse 3 did not eatafter this experience, and subsequently died at about 30 days after theexperiment. We did not observe any external injuries on Nurse 3. Weattribute this to stress and possibly shock from encounter with thehigh-pull-force magnet in the maze.

Example 6 N48 Neodymium-Iron-Boride (NdFeB) Nickel-Coated PermanentMagnet Terminate Tonic Immobility

Juvenile lemon sharks (Negaprion brevirostris) and juvenile nurse sharks(Ginglymostoma cirratum) that had been placed in tonic immobility weresubjected to the magnetic field of an N48 neodymium-iron-boride (NdFeB)nickel-coated 4″×1.5″ cylinder permanent high-pull-force magnet and wereobserved. The high-pull-force magnet had the following characteristics:

-   -   Calculated Pull Force 521 pounds    -   Residual Induction: Coercive 14 KGs    -   Force: 11.0 KOe    -   Intrinsic Coercive Force: 2:: 12.0 KOe    -   Maximum Energy Produce: 48 MGOe    -   Curie Temperature: 320° C.-330° C.    -   Vickers Hardness: Working 500-600    -   Temperature: Temperature <−80° C.    -   Coefficient −0.11% per ° C.

A DC milligauss magnetometer (Alpha Labs, Inc.) was used to recordmagnetic field strength during the study. The magnetometer sensor wassecured to the top of a nonmagnetic Yi″ polyvinyl chloride stake, whichwas driven vertically into the sand at the test site. The magnetometersensor was submerged for the study. Water depth did not exceed 36″ atthe test site. A meter-long rule was secured to the magnetometer sensor.

A control test was preformed in order to determine if the activatedmagnetometer sensor would terminate tonic immobility. The magnetometerwas set to zero to compensate for the background magnetic field of theearth, which allowed fluctuations from the permanent magnet to bemeasured. A juvenile female lemon shark in tonic immobility was helddirectly at the magnetometer sensor. Tonic immobility did not terminate.The magnetometer readings did not fluctuate when the lemon shark was inproximity to the sensor demonstrating no change in magnetic fieldstrength.

Two 4″ cylindrical N48 grade NdFeB nickel-coated permanenthigh-pull-force magnets (nominal strength 14000 gauss, pull force about521 pounds) were calibrated by observing the magnetic field strengthversus distance from the magnet under water. The following data wererecorded:

TABLE 6 Distance milliGauss (mG) 1.5 m +191 1.0 m +524 0.9 m +700 0.8 m+920 0.7 m +1310 0.6 m >+2000

Because the maximum reading of the magnetometer used in the experimentswas 2000 mG, magnetic fields at distances less than 0.6 m from themagnet were calculated using a standard gauss calculation for acylindrical magnet. In this case, we used the calculator provided atvV\Vw.arnoldma_gnetics.com/mtc/calc_g_auss cyl.htm. The followingparameters were in-put into the magnetic field calculator: L=4 in.;D=1.5 in; Br=13,000 G; Z=distance from magnet.

With a juvenile shark subject to tonic immobility at the magnetometersensor, the permanent magnet was moved along a stationary rule, levelwith the shark and the sensor, towards the shark. The high-pull-forcemagnet was not moved faster than 0.1 mis toward the shark. The followingresults were obtained for termination of tonic immobility. (Note: +denotes the north pole, electrically on the gaussmeter.)

TABLE 7 Distance Magnetic (m) to Pole terminate Facing tonic CalculatedSpecimen Shark immobility mG Juvenile lemon shark + 0.1 246971 Juvenilelemon shark − flipped + 0.0 3130415 Juvenile nurse shark − 0.3 14477Juvenile nurse shark + 0.3 14477 Juvenile nurse shark + 0.2 44154Juvenile nurse shark − 0.2 44154 Juvenile nurse shark + 0.2 44154Juvenile nurse shark + 0.2 44154

Since the movement of the permanent high-pull-force magnet underwaterinduces an electrical current, the next study moved the tonic sharktoward two stationary high-pull-force magnets, each fixed at 1.5 m fromthe sensor. Tonic immobility was terminated when the sharks were broughtwithin 0.2 m of the high-pull-force magnet faces.

It was consistently observed that tonic sharks awoke by turning awayfrom the magnet's face. This was independent of the pole of thehigh-pull-force magnet, and the orientation of the shark's head towardthe magnet. More violent responses occurred when the shark's head wasoriented 90 degrees to the high-pull-force magnet face, rather than 0degrees (nose-to-magnet face).

The movement of the shark toward the high-pull-force magnet, as well asthe movement of the high-pull-force magnet toward the shark might createelectric current and awaken the shark. To eliminate this possibility,care was taken not to move the high-pull-force magnets in a rapidmanner.

Example 7 Electromagnetic Device with Lower Magnetic Strength Did notTerminate Tonic Immobility

In a first experiment using an electromagnetic device, an iron-coreelectromagnet was secured to the end of a PVC pole, and energized with12 VDC using a marine wet-cell battery. Current was monitored using adigital multimeter. A tonic juvenile female lemon shark was held at themagnetometersensor, while the tip of the electromagnet was moved. Thefollowing results were obtained:

TABLE 8 Distance between AMPS to shark and electromagnet @ Measuredelectromagnet 12VDC mG Shark's Response 1.0 m 6.27A −10 Did not awaken0.5 m 6.28A −139 Did not awaken 0.0 m 6.24A −1700 Did not awaken 0.0 m6.16A (reversed polarity) >2000 Did not awaken

In a second experiment using an electromagnetic device, a commercial1000 lb.-strength waterproof electromagnet, produced by LOCKNETICS,INC., was energized with 12V DC using a marine wet-cell battery.According to the product specifications, this magnet draws a consistent30 A at 12 VDC, which exceeded the capability of the digital multimeter.A tonic juvenile female lemon shark was held at the magnetometersensor,while the face of the electromagnet was moved. The following resultswere obtained:

TABLE 9 Distance between AMPS to lemon shark and electromagnet @Measured Lemon shark's electromagnet 12VDC mG Response 1.5 m 30A −20 Didnot awaken 1.0 m 30A −40 Did not awaken 0.5 m 30A −280 Did not awaken0.5 m 30A, but flickered −280 Did not awaken powered randomly instead ofa constant supply 0.0 m 30A >2000 Did not awaken 0.0 m 30A reversedpolarity >2000 Did not awaken randomly

These two experiments demonstrate that despite strong electromagneticfields in close proximity, such fields were not sufficient to terminatetonic immobility in juvenile nurse sharks and lemon sharks. The magneticfield strength was not sufficient to terminate tonic immobility.

However, as seen above, a powerful field from an NdFeB permanenthigh-pull-force magnet is sufficient to terminate tonic immobility injuvenile nurse sharks and lemon sharks. It is believed that a fieldstrength of approximately 50 G at least 0.1 m distance from amelasmobranch reliably terminates tonic immobility. 50 gauss is about 100times the Earth's magnetic field.

Example 8 Bracelet, Belt or Other High-Pull-Force Magnet as Repellent ofShark

Two lemon sharks in an outdoor pen were placed in tonic immobility. Ablinder was placed between the sharks and a magnet having about 191pounds of pull force and a nominal strength of about 14000 gauss. Uponintroducing the magnetic bar up to about 0.2 meters behind the blind,tonic immobility was terminated and the sharks violently moved inorientation away from the high-pull-force magnet.

Example 9 Bracelet as Repellent of Shark

Research on captive nurse sharks suggests that a high-pull-forcebracelet is effective in repelling sharks. Using a vinyl-walled tank,high-pull-force magnets were waved outside the tank wall near a restingnurse shark inside the tank. The shark had no olfactory, motion, sound,or visual clues. In seven separate observations, the nurse shark alwaysrapidly fled from its resting site once the high-pull-force magnet waswaved on the tank wall near the subject. When non-magnetic objects werewaived at the same position outside the tank, no change in behavior wasobserved.

Example 10 Target Fish not Repelled by High-Pull-Force Magnets

Preliminary research conducted on the effects permanent magnetic fieldson adult cobia, Rachycentron canadum, suggests that very strong magneticfields (i.e. >14,000 Gauss or 14 Tesla) produced by “rare earth” magnets(NdFeB) (13,800 gauss, 110 pounds pull force) had little effect on cobiaduring feeding. Digital video of cobia feeding within 5 cm of the “rareearth” high-pull-force magnet was recorded. In three trials sardineswere offered to the cobia on PVC tubes with no magnets inside. In threesubsequent trials sardines were offered on PVC tubes with ahigh-pull-force magnet inside. The high-pull-force magnet was composedof 4 discs (I″diameter×¼″ height) stacked on top of each other withTeflon™ rings between each magnet.

In another control test, squid was presented to yellowfin tuna in thepresence of an NdFeB high-pull-force magnet of grade N48. A horizontalpole with six squid (and a corresponding high-pull-force magnet) hungequally spaced along the pole was presented to the tuna. The pole waslowered into the tank. The tuna took the bait in the presence of thehigh-pull-force magnets. The tuna were not repelled.

The ability to selectively repel elasmobranch is useful both forlongline fishing applications (to catch target fish and avoid killingelasmobranch) and for human applications, particularly for divers andsnorkelers (to repel elasmobranchs and not repel fish).

1-34. (canceled)
 35. A method for repelling an elasmobranch comprising: placing a permanent high-pull-force magnet that generates a magnetic field sufficient to repel an elasmobranch into the environment of the elasmobranch wherein the high-pull-force magnet comprises the following properties: (i) a pull force of greater than about 50 pounds; (ii) a nominal strength of greater than about 5000 gauss alone or in combination with one or more other magnets; (iii) a greater than about 5 gauss of magnetic strength at a distance of about 0.01 m to about 1.0 m; and wherein said permanent high-pull-force magnet is attached to a surfboard.
 36. The method of claim 35, wherein the permanent high-pull-force magnet is attached to the magnet through integration of the magnet into the surfboard.
 37. The method of claim 35, wherein the attachment of the high-pull force magnet to the surfboard is such that it trails behind the surfboard.
 38. The method of claim 35, wherein the high-pull-force magnet is coated to prevent corrosion when the magnet is placed in water.
 39. The method of claim 35, wherein the high-pull-force magnet is a neodymium-iron-boride magnet.
 40. The method of claim 39, wherein the neodymium-iron-boride magnet is coated with nickel.
 41. The method of claim 35, wherein the high-pull-force magnet has a shape of a cylinder, a cone, a circle, a cube, a disk, a bar, a sphere, a plate, a rod, a ring, a tube, a stick, a block, or a tapered cone.
 42. The method of claim 35, wherein the high-pull-force magnet comprises a hollow portion.
 43. The method of claim 35, wherein a plurality of high-pull-force magnets are arranged together in a ring.
 44. The method of claim 35, wherein the high-pull-force magnet is capable of spinning.
 45. The method of claim 35, wherein the high-pull-force magnet has a pull force of greater than about 100 pounds.
 46. The method of claim 35, wherein the high-pull-force magnet has a pull force of greater than about 200 pounds.
 47. The method of claim 35, wherein the high-pull-force magnet has a nominal strength of greater than about 10,000 gauss alone or in combination with one or more other magnets.
 48. The method of claim 35, wherein the high-pull-force magnet has a nominal strength of greater than about 20,000 gauss alone or in combination with one or more other magnets.
 49. The method of claim 35, wherein the high-pull-force magnet has up to about 14,000 gauss of magnetic strength at a distance of about 0.01 m to about 0.5 m.
 50. The method of claim 35, wherein the high-pull-force magnet has up to about 320 gauss of magnetic strength at a distance of about 0.1 m to about 0.4 m.
 51. The method of claim 35, wherein the high pull force magnet is placed in close proximity to an elasmobranch. 